Veteran PPPL engineer Tim Stevenson receives Distinguished Engineering Fellow award for his contributions to two flagship fusion experiments

Written by
Jeanne Jackson DeVoe
Dec. 21, 2021

Tim Stevenson, an engineer who has been an integral part of major experiments in his 37-year career at the U.S. Department of Energy’s (DOE) Princeton Plasma Laboratory (PPPL), was named a Distinguished Engineering Fellow by PPPL for his contributions to two flagship experiments in the drive to bring to Earth the fusion energy that powers the sun and stars. The honor, presented by Steve Cowley, PPPL director, includes an award of $7,500.

Stevenson received the award at the Laboratory’s State of the Lab address on Dec. 17. He was cited “for excellence in operations and management of heating systems on the National Spherical Torus Experiment-Upgrade (NSTX-U) and the development and operation of these systems in support of the Tokamak Fusion Test Reactor (TFTR) deuterium-tritium experiments, which produced a world record 10.7 million watts of controlled fusion power.”

Stevenson said he was touched to receive the award. “I was able to contribute along with the beam team to physics research and making new knowledge,” he said. “What an honor!”

Steve Cowley, PPPL director, announced the award during his Dec. 17 State of the Laboratory address that reviewed major developments over the past year. Three physicists: Raffi Nazikian, Jong-Kyu ark and Qiming Hu were also honored for their contributions to fusion energy research with the Kaul Foundation Prize for Excellence in Plasma Physics Research and Technology Development. To read that story click here.

Cowley said during the online presentation that Stevenson is “one of the stalwarts of the Lab.” “He has an amazing set of skills in operations, we lean on him very hard, and he has broad shoulders and a placid manner,” Cowley added. “He has steered the Lab for decades now. He was one of the stalwarts of TFTR and the world record in 1994. I just want to thank Tim for this amazing work. He’s our Distinguished Fellow and Tim, many more years please!”

Michael Ford, head of Engineering, said the award is well-deserved. “Tim has provided decades of outstanding service to PPPL, first as a technical expert and operator and more recently as a group leader, where he ensures the lessons he has learned are transferred to the next generation of engineers and technicians,” Ford said. “He is most deserving of this recognition."

Bob Ellis, PPPL’s chief engineer, who received the award in 2012, said he was pleased to see Stevenson honored. "It is great to see Tim recognized with this award,” Ellis said. “I have known and worked with him for over 30 years. He played a major role in the development and operation of TFTR neutral beams in support of machine operations, and especially the historic D-T experiments. His extensive knowledge of our neutral beam systems was a great help as the TFTR beams were repurposed for NSTX and NSTX-U. His support of the NSTX-U Recovery project is invaluable."

Worked on neutral beams since starting in 1984

Stevenson has been working on neutral beams since he first arrived at PPPL in 1984 when the massive TFTR experiment was starting its research. He graduated from Lehigh University with a bachelor’s degree in electrical engineering and a minor in economics in 1982. He then worked for two years as an electrical engineer at an original equipment manufacturer building surface mining excavation equipment before coming to PPPL.

The neutral beams are vital to fusion experiments, Stevenson explained. They act as a “blow torch,” shooting neutral particles into the ionized gas called a plasma inside the fusion device called a tokamak. The particles are then re-ionized and heat the plasma and stir the pot to keep the plasma moving.

When Stevenson arrived at PPPL, TFTR was operating with one beam line and the team was redesigning and upgrading the lines to make them work. The next year, another line was added and by 1986 four beam lines were running.

In 1991, the machine shut down and the team was tasked with reconfiguring the beam lines for deuterium-tritium operations. Stevenson became the head of neutral beams the following year. The experiment started up again with deuterium-tritium in 1993 and operated through 1997. In 1994, TFTR achieved world-record power that made headlines around the world. “We got to build it, test it, install it, run it, do the whole life cycle of being able to operate it, and it’s kind of an old-fashioned hot rod process,” Stevenson said. “You figure out what is weak, make it strong. I’ve worked with fantastic people, but it’s also been a fantastic full life-cycle engineering process and I’ve just really been deeply involved in it.”

One of the neutral beams was repurposed for the National Spherical Torus Experiment (NSTX) experiment that began operating in 1999.  In addition to running the neutral beams, Stevenson was a physics operator working with physicists in the control room to operate the device. He also branched out and began chairing design reviews and “got to see the incredible work product of our Engineering Department.” He served as head of the Project Management Office from 2010 to 2018.

Doubling the power of NSTX

When the NSTX was shut down to create a more powerful machine, Stevenson and the beam team added a second neutral beam that doubled the machine’s heating power. With two neutral beams, the NSTX-U is capable of achieving 15 megawatts or 15 million watts of neutral power during experiments.

While continuing as head of the Heating Group, which has more than 25 staff members, Stevenson serves in multiple roles at PPPL. He is an associate project manager of the NSTX-U Recovery Project, which is rebuilding several components of the machine, and the head of NSTX-U Engineering Operations. He is overseeing the installation of new safety systems in compliance with the federal Accelerator Safety Order and is also in charge of commissioning NSTX-U once it’s ready to resume operations. In his spare time, he is an emergency director for the Emergency Response Organization. He also has served as a tour guide, providing tours of the Laboratory to everyone from Boy Scouts to college students.

Stevenson is married to Dolores Stevenson, an administrator at PPPL who retired a few years ago after 36 years at the Laboratory. He enjoys oil painting, playing the guitar, weightlifting, running and cycling, and gardening and reading books about history.

He remains enthusiastic about the many hats he wears as he looks back over his long career.

“I’ve learned so much,” he said. “It’s just been unimaginable to have this kind of engineering career. It's absolutely unimaginable to me. It still is!”

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